Researched effects of carbs on IF/leangains and I need a bit of help putting it all together.

Background

I did a 2 month cut and got down to lower 20% bodyfat. Did it through a high-protein/low-carb diet while working 5/3/1 bbb. At the point where I need to add more calories to keep up with lifts so I am going leangains. To bump up my calories I am adding starches back into my diet. My question was what is the best way to incorporate those calories to utilize the energy for lifts but avoid gaining weight.

As always the research contradicted with people in the paleo camp claiming insulin levels mattered the most and so starches should be out. Then I read up on the leangains camp that called all of that to be bullshit. Their claim is overall calories matter and the insulin is just incidental to bodyfat (not a CAUSE of bodyfat).

This just seems like a pissing contest.

Question

Am I right to disregard everything I was taught about carbs and worry about calories over grams of carbs. As in, should I know the amount of protein and fat I need. Do I just fill in the gap to my desired calorie count with carbs?

On that note, it is "common knowledge" at this point the difference between simple and complex carbs. But if at the end of the day only calories matter, then besides fiber what is the purpose of choosing complex carbs? As long as you stick to your calorie count, it shouldn't matter?

Sorry if this is a bit convoluted, but I am trying to connect the dots.

tl,dr; Doing IF/leangains. Need more calories. How to incorporate carbs?